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PUMPING LIFE:
THE HEART AND
CIRCULATORY SYSTEM
1 videocassette . . . . . . . . . . . . . . . 22 minutes
Copyright MCMLXXXIX
Rainbow Educational Media
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TABLE OF CONTENTS
Introduction ........................................................................ 1
Program Summary.............................................................. 1
Learning Objectives............................................................ 3
Discussion Questions.......................................................... 5
Suggested Activities. .......................................................... 8
Credits............................................................................... 18
Glossary............................................................................ 19
Bibliography..................................................................... 20
Related Videos From Rainbow......................................... 21
Script................................................................................. 10
INTRODUCTION
Pumping Life: The Heart and Circulatory System describes
the structure and function of the human circulatory system
and heart at a level of detail appropriate for a middle-school
audience.
The circulatory system is often a difficult subject for
students at this level to grasp, and this video can either
stand alone as an introduction to the topic or reinforce what
students have already studied.
Throughout, lively examples are used to maintain student
interest. A science-fiction-like opening compares the circulatory system to a complex system of pipes and vessels. A
dramatic scene with an ambulance and heart attack victim
focuses attention on disorders of the circulatory system.
Clear and colorful graphics and animation help students
understand concepts that might otherwise be difficult for
them to comprehend. The route blood takes through the
chambers of the heart and the blood vessels is displayed
step by step. The structures and functions of the heart,
arteries, veins, and capillaries are shown.
Sound effects, music, and alternating male and female
narrators are used to stimulate student interest further and
to emphasize the importance of the heart and circulatory
system.
PROGRAM SUMMARY
Pumping Life: The Heart and Circulatory System opens
with dramatic, science-fiction-like graphics showing an
elaborate system of pipes and a pump. The viewer is asked to
imagine such a system, one that is over 96,000 kilometers long
and that has a pump that can work continuously for more than
70 years. The graphics show the human body as the narrator
explains that such a system is not science fiction but
actually exists within each of our bodies. It consists of the
blood, blood vessels, and heart.
The video goes on to explain that the human body has
several systems that enable us to run, play, work — even to
think. The circulatory system is one of these systems. It
serves as a transport network that moves materials to and
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© MCMLXXXIX Rainbow Educational Video, Inc.
from the body's cells. It brings nutrients and oxygen to the
cells from the digestive system and the lungs, and it carries
carbon dioxide from the cells back to the lungs. It carries
other wastes to the kidneys, which remove them from the
blood and excrete them as urine.
The program examines the three major types of vessels
that make up the circulatory system — arteries, veins, and
capillaries. Students could learn that arteries carry blood
away from the heart, and they see how the thick elastic walls
of arteries expand and contract as the heart pumps blood
through them. This regular stretching of the artery walls is
called pulse.
The program describes how veins carry blood back to the
heart and how one-way valves in the veins allow blood to
flow in only one direction. The video then shows how arteries
and veins are linked by tiny vessels called capillaries that lie
adjacent to almost every cell in the body. Graphics show how
the thin walls allow oxygen to pass from the blood to the
body's cells and for carbon dioxide to pass the other way,
from the cells to the blood.
The program describes the major components of blood,
including plasma, a watery liquid containing chemicals and
food; white blood cells that help fight disease; red blood
cells that pick up oxygen from the lungs and carry it
throughout the body; and platelets that start the process of
clotting and help stop bleeding.
The next section of the program examines the pump that
pushes the blood through the circulatory system — the
human heart. Graphics show that the heart is made up of four
chambers — two atria on top and two ventricles directly below
the atria.
The program then takes students on a journey through the
heart and circulatory system, starting and ending in the right
atrium. The program emphasizes that the heart is not one
pump but two. The right pump takes blood from the body
and sends it to the lungs where carbon dioxide waste is
unloaded and a fresh supply of oxygen is picked up. The left
pump takes this oxygen-rich blood from the lungs and sends
it to the body.
The program stresses that our lives depend on the con-
tinuous beating of our hearts. To help students understand
how strong the heart is, the narrator asks them to open and
close their fists 70 times in a minute, explaining that this is
the average heart rate for an adult. The narrator then
describes how the average person's heart will beat over 2
billion times in a lifetime.
The program goes on to explain that a person's heart does
not beat at the same rate all the time. Instead, heart rate
varies according to a person's level of activity. To illustrate
this point, the video follows a girl through a typical day,
showing how her heart rate changes according to her activity.
To introduce the next section of the program, a dramatic
sequence showing an ambulance crew and a heart attack
victim makes the point that heart and circulatory disorders
are the nation's number one killer. The program describes
how fatty deposits can build up in arteries, leading to a
stroke or a heart attack. It emphasizes that while most of the
victims of heart attacks and strokes are middle-aged or
older, problems can begin to develop much earlier, even
among the same age as the students who are viewing the
program.
The program goes on to describe the link between a highfat, high-cholesterol diet and cholesterol and heart and circulatory disorders. Ice cream, hot dogs, and other fatty foods
are cited as foods that are high in fat, and the program recommends a healthy diet of vegetables, fruits, and whole
grains to help prevent cardiovascular disorders. The program
also stresses the importance of exercise in building a strong,
healthy heart.
Finally, the video summarizes the key points of the program.
LEARNING OBJECTIVES
After viewing this program, students should be able to:
1. understand and describe the importance of blood to the
human body
2. understand and describe how the body's circulatory
system works and its importance to the human body
3.
understand and describe the functions of the three
major types of blood vessels, arteries, veins, and capillaries, specifically:
— that arteries carry blood away from the heart.
— that capillaries are the smallest blood vessels and
are the sites where food, oxygen, and carbon
dioxide enter and leave the bloodstream.
— that veins carry blood back to the heart.
4.
describe the physiology of the heart; specifically:
— that the heart consists of two pumps. The right
pump collects blood from the body and sends it
to the lungs. The left pump collects blood from
the lungs and sends it to the body.
— that each pump has two chambers: the atrium and
the ventricle.
— that the atria receive blood.
— that the ventricles pump blood.
5.
describe the path of blood through the heart and the
circulatory system.
6.
understand what heart rate is, how average heart rate
varies among individuals, and how and why an individual's heart rate changes in the course of a day.
7.
understand that diseases of the heart and circulatory
system are the nation's number one killer, and that the
groundwork for such diseases is often laid when people
are young.
8.
understand that a high-fat, high-cholesterol diet has
been linked to cardiovascular disease.
9.
understand the importance of a healthy diet and regular
exercise to the well-being of the heart and circulatory
system.
DISCUSSION QUESTIONS
1.
What are some of the things that cells need in order
to function?
[Food and oxygen are emphasized in the video.]
2.
Name a waste product that cells produce as they do
work.
[Carbon dioxide.]
3.
How do humans differ from single-celled organisms,
such as amoeba, in the way they obtain oxygen and
food and get rid of wastes such as carbon dioxide?
[Since it consists of only a single cell, an amoeba can get
food and oxygen directly from the water that surrounds
it. These materials flow into the amoeba through its cell
wall, and carbon dioxide waste flows out. The human
body, however, is composed of many cells, and most of
these cells are surrounded by layers and layers of other
cells. Therefore, human cells cannot get the raw materials
they need directly to their environment, nor can they
release wastes directly into their environment.]
4.
Why is the circulatory system called a "transport
system"?
[Among other things, it transports nutrients from the
digestive system to the body's cells, carries oxygen from
the lungs to the cells, takes carbon dioxide waste from
the cells back to the lungs, and carries other types of
wastes to the kidneys.]
5.
What are the three main types of vessels in the circulatory system?
[Arteries, veins, and capillaries.]
6.
Describe the main functions of each type of vessel.
[Arteries carry blood away from the heart to the body's
cells. Veins carry blood back to the heart. Capillaries link
arteries and veins. They also allow oxygen and food to
pass from the blood into cells, and wastes to pass from
cells back into the blood. 1
7. What are the major components of blood?
[Over half of blood consists of plasma, a liquid composed
mostly of water. Plasma also contains food, chemicals,
and wastes. Blood also consists of cells and cell parts,
including red blood cells, white blood cells, and platelets.]
8.
What do red blood cells do?
[They pick up oxygen in the lungs and carry it to cells
throughout the body.]
9.
Why are white blood cells important?
[They help defend the body against disease.]
10. Describe what platelets do.
[They start the process of clotting. When you cut yourself,
for example, platelets cause the growth of a threadlike net
that helps stop the bleeding.]
11. What are the two different kinds of chambers in the
human heart?
'
[Atria and ventricles.]
12. Describe the path of blood through the circulatory
system, starting and ending at the right atrium.
[Blood flows from the right atrium through a one-way
valve into the right ventricle. The right ventricle contracts,
forcing blood out of the heart into a large artery. This
artery forks, taking blood to the lungs where the arteries
branch into smaller and smaller arteries. These lead to
capillaries that are next to tiny air sacs in the lungs. Here,
carbon dioxide passes through the capillary walls into the
lungs, and oxygen flows from the lungs into the capillanes.
The capillaries lead to veins; these take the blood back to
the heart. The blood flows first into the left atrii. and then
through a one-way valve into the left ventricle. When the
left ventricle contracts, it forces the blood into the
aorta, the body's largest artery. From the aorta, branching
arteries lead into capillaries. Here blood gives up oxygen
to cells and takes on carbon dioxide and other wastes.
The blood then returns via veins to the right atrium of the
heart, completing the cycle.]
Why is the heart often considered to be two pumps
rather than one?
[The right side of the heart collects blood from the body
and sends it to the lungs, where carbon dioxide waste is
unloaded and oxygen is picked up. The left side of the heart
collects this oxygen-rich blood and sends it throughout
the body.]
Why does a person's heart beat at different rates in
the course of a day?
[One reason is that heart rate is affected by the body's
energy needs. When we are more active, our cells need
more oxygen and fuel, and the heart beats faster.]
Describe some of the things that might contribute to
disorders of the heart and circulatory system.
[Smoking and diet are mentioned in the program.]
How can diet contribute to problems of the heart and
circulatory system?
[A diet high in fat and cholesterol can lead to the buildup of
fatty deposits in arteries. These deposits can impede and
even block entirely the flow of blood, possibly causing a
stroke or heart attack.]
Are problems of the heart and circulatory system
limited to people who are middle-aged or older?
[No. While younger people rarely have heart attacks or
strokes, the buildup of fatty deposits in the arteries can
happen even in children and teenagers.]
18. Name some foods that are beneficial for the heart and
circulatory system.
[Fruits, vegetables, and whole grains are cited in the program.]
19. Why is exercise good for the heart?
[The heart is a muscle; it can be made stronger with exercise. A strong heart can pump more blood with each beat;
this allows it to rest longer between beats.]
SUGGESTED ACTIVITIES
The following activities are meant to enhance students'
understanding of topics covered in the program and to introduce them to areas not covered.
1.
Heart rate: taking pulse. Students can learn to determine
their own heart rates by taking their pulses. To determine pulse, students should place their second and index
fingers on the inner wrist. They should move their
fingers around until they feel the throbbing artery.
Students should then count the numbered pulses over a
fifteen-second period and multiply this number by four.
This will determine pulse rate in beats per minute.
2.
Heart rate: variations among individuals. Students can
investigate the range of resting heart rates among
members of the class. All students should sit still for five
minutes and then take their pulses to determine heart
rate in beats per minute. Once the results have been
recorded, students should determine the highest and
lowest rates and the class average.
3.
Heart rate: variations in a single individual due to
changes in physical activity. The program describes how
heart rate varies throughout the day according to a person's level of physical activity. Students can investigate
further the effects of physical activity by examining vari
ations in their own pulses. Students should take their
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pulses after being still for several minutes. Then they
should exercise by running in place for three minutes
and check their pulses once more to see how the exercise
affects their own heart rates.
4.
Heart rate: effects of stress. While physical activity directly affects heart rate, there are other factors that can
cause variations in heart activity. One of these is stress.
This activity requires two students: one to be the subject, and another to be the experimenter, checking the
subject's pulse and administering a series of questions
to the subject. First, the subject should sit still for several
minutes, pressing the subject to deliver speedy answers.
As soon as the questioning is over, the experimenter
should check the subject's pulse again to see if heart
rate has risen in response to the stress of the questioning
session.
5.
Heart disease and diet.
— Students could write to the American Heart Association for their most recent recommendations concerning foods that are healthy for the heart and circulatory system.
— Students could invite a nutritionist to speak to the
class about the role of diet in cardiovascular health.
— Students could investigate the different types of
cholesterol. As the program states, not all cholesterol is
bad. One type of cholesterol, HDL, is considered
beneficial because it helps remove other types of
cholesterol from the bloodstream. Students could
research the most recent information about the roles
of different types of cholesterol, and the levels and
ratios of different types of cholesterol in the blood
that are considered healthy or unhealthy.
6.
The structure of the heart. While the human heart has
four chambers, the hearts of many other vertebrates are
different. The heart of a fish, for example, has only two
chambers, while that of an amphibian has three. Students could study and report on the hearts and cir-
culatory systems of other animals and compare them
with the human heart and circulatory system.
7.
The history of our understanding of the heart and circulatory system. The story of how we acquired our understanding of the functioning of the heart and circulatory system and the role of blood is one that spans many
centuries. Students could research and report on how
we acquired this knowledge. They could investigate early
theories, such as those of Aristotle and Galen, and show
how these theories were replaced or modified by such
scientists as William Harvey, who was the first to demonstrate the function of the heart and the circulation of
blood.
SCRIPT
Imagine a system of pipes that is over 96,000 kilometers long
— 59,000 miles.
Then imagine a pump that is part of this system — a pump
that can work continuously for more than 70 years, never
pausing for more than a fraction of a second.
Now think of the fluid that is pumped through this pipeline
system. What if that fluid could provide energy and get rid
of poisonous wastes? What if it even helped capture and
destroy harmful organisms?
Is this system part of a science fiction novel, an imaginative
vision of the future?
Mo. It is real. It exists today in each of our bodies.
It is the incredibly intricate system of vessels that provides
all the different parts of the body with life-sustaining blood.
It is the body's circulatory system. . . .
And the pump at the heart of this system is the heart itself.
TITLE Pumping Life: The Heart
and Circulatory System
The human body is more versatile and complex than any
machine ever invented.
10
How is it that we can do so many different things?
The body has several systems that together make it possible
for us to play, work, and even think.
Without these systems, life itself would not be possible.
One of these systems is the circulatory system. To understand how the circulatory system works, we must examine
how the body operates at a level we can't perceive with our
eyes alone. We need to come down to the microscopic level of
cells. Cells are the basic building blocks of life. They make up
the skin, the bones — all the tissues and organs of the body.
Cells do the body's work. Nerve cells, for example, relay
messages in the brain.
There are fiber-like muscle cells. . . and many other types
of cells. All together there are trillions of cells in the body.
But in order for the body to function, these cells must have
food and oxygen. And as they work, cells produce wastes,
such as carbon dioxide, that the body must get rid of.
Even organisms that consist of only a single cell, such as
this amoeba, must have food and oxygen, and get rid of
wastes.
For an amoeba, this is relatively easy. Food, oxygen, and
other raw materials flow into the amoeba from the water that
surrounds it, and carbon dioxide and other wastes flow out.
But the human body is different. It has many cells and
most of these cells are surrounded by layers of other cells.
So how can food and oxygen reach our cells, and how can
they get rid of wastes?
This is where the circulatory system comes in. It provides a
transport system to move materials to and from all the cells
of the body.
What do we mean by a transport system?
Well, think of some transport systems that you know about.
There are highways where cars and trucks transport goods
and people all around the country.
There are also river systems on which barges and ships
carry freight between different ports.
A river system may be most like the transport system within
the body.
But inside the body, instead of rivers there are many dif-
11
ferent pipe-like vessels. And instead of flowing with water,
these vessels contain blood.
This system of blood and blood vessels transports materials
to and from all parts of the body.
It carries food from the digestive system to cells, throughout
the body, which use this food for energy and growth.
This transport system also carries oxygen from our lungs
to the body's cells.
And it brings carbon dioxide waste from the cells back to
the lungs, where it is exhaled.
Besides helping to get rid of carbon dioxide, it takes other
wastes to the kidneys. Acting as a kind of disposal system,
the kidneys remove these wastes from the blood and excrete
them from the body in the form of urine.
Let's take a closer look at the different types of vessels that
are part of the circulatory system.
The vessels that carry blood away from the heart are called
arteries. The walls of arteries are thick, muscular, and elastic.
With each beat of the heart, these walls stretch as the
heart pumps blood through the arteries. After the blood
passes through, the walls relax. This regular stretching and
relaxing of the artery walls is called pulse.
You can feel the pulse of an artery in your wrist. Feeling
your pulse is one way of seeing how fast your heart is beating.
Different kinds of vessels carry blood back to the heart.
These are called veins. Veins are thinner and less muscular
than arteries.
Blood moves through the veins because muscles in your
arms and legs squeeze the veins, forcing blood through valves
or gates. When muscles relax, these valves slam shut, preventing blood from flowing backwards, away from the heart.
Arteries and veins are linked by a network of tiny blood
vessels called capillaries.
Almost every cell in the body lies next to a capillary. The
walls of capillaries are very thin, only one cell thick.
Because these walls are so thin, oxygen and food can easily
pass from the blood through the capillary walls and into
cells.
At the same time wastes, such as carbon dioxide, can pass
out of the cells into the capillaries.
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Capillaries are so small that they can only be seen with the
help of a microscope; but together with arteries and veins,
they form a network so vast that, if all the blood vessels in the
body were l ined up end to end, they would stretch for tens of
thousands of miles.
Let's take a closer look at what flows in this network of
different types of blood vessels.
We all know what blood looks like. If you prick your finger, you see that blood is liquid and red in color.
If we separated the major components of blood in a test
tube, we'd see that over half of it — about 55% — consists of
a liquid called plasma. Most of this liquid is water. In addition,
plasma contains food, hundreds of chemicals that the body
needs, and some wastes.
The other part of our test tube of blood contains several
different types of blood cells and cell parts.
Most are red blood cells. Red blood cells act like freighters.
They pick up oxygen from the lungs and they carry it to
cells throughout the body, where they unload this life-sustaining cargo.
Here we see red blood cells with the help of a powerful
electron microscope. In a single drop of blood there are
millions of these cells, which look a little like donuts with
the centers filled in.
Blood contains other types of cells, too. White blood cells
help defend the body against disease-causing bacteria and
other harmful microorganisms.
Here we see a white blood cell destroying some bacteria
by actually eating them before they can do harm.
Blood also protects us in other ways. Have you ever wondered why you don't keep on bleeding after you've pricked
your finger?
Well, blood contains cell parts called platelets that start
the process of clotting when you cut yourself.
Platelets cause the growth of a thread-like net. Red blood
cells get caught in this net, stopping the bleeding.
Blood has too many roles to describe in detail here. But in
order for blood to do its job, it must continually flow
throughout the body. A pump is needed to push blood
through the circulatory system.
13
The heart is this pump. The human heart is only about as
big as your fist and weighs less than a pound. But despite its
size, the heart is very powerful because it is almost all
muscle.
If you could look inside this muscle, you would see that
the heart has four chambers, or hollow spaces.
The two top chambers are called atria.
Each atrium is connected to another chamber beneath it
called a ventricle. But while each atrium is connected to the
ventricle below it, there is no connection between the right
side of the heart and the left.
In fact, there is a thick muscular wall that separates the
two sides of the heart. It is almost as if there were two hearts
instead of one.
To see why the heart is divided like this and how blood gets
from one side of the heart to the other, let's follow blood as it
makes its trip through the body.
We'll start our journey in the right atrium, which from our
vantage point appears on the left. Veins from the body empty
their blood here. This blood is high in carbon dioxide that has
been picked up from cells throughout the body. In real life
this blood has a dull red color; but to make things clearer, we'll
show it as blue.
After blood collects in the right atrium, it flows through
an open valve into the right ventricle.
This valve then slams shut as the right ventricle contracts,
preventing blood from flowing back to the atrium.
When the ventricle contracts, it forces the blood into a large
artery that forks, taking blood to both lungs. Within the
lungs, the arteries branch into smaller and smaller arteries
that lead to capillaries.
In the lungs, the capillaries are close to many tiny, balloonlike air sacs. Carbon dioxide flows into these air sacs through
the capillary walls, and oxygen flows from the air sacs into
the capillaries. This oxygen gives the blood a bright red color.
This bright red, oxygen-rich blood moves from the lungs
back to the heart through a series of veins. . . .
And empties into the left atrium.
This explains how blood gets from the right side of the
heart to the left. But the journey is not complete.
14
The left atrium releases this oxygen-rich blood through
another one-way valve into the left ventricle.
When the left ventricle contracts, it forces blood into the
body's largest artery, called the aorta.
The blood flows through the aorta to other arteries that go
throughout the body.
These branch into capillaries. Here, as we've seen before,
oxygen and food pass from the blood into cells.
Carbon dioxide passes the other way from cells to the
blood.
The blood, now poor in oxygen, returns by way of veins
to the right atrium, where the cycle begins again.
So the heart is actually two pumps, not one.
The right pump takes blood from the body and sends it to
the lungs where carbon dioxide waste is unloaded and a
fresh supply of oxygen is picked up.
The left pump collects oxygen-rich blood from the lungs
and sends it to the body where cells use the oxygen. Our
lives depend on this cycle continuing without interruption.
In fact, as we go about our lives, our hearts are beating constantly, resting only briefly between beats.
This continuous beating points to the fact that the heart is
an extraordinarily strong muscle. To get an idea how strong, try
this:
Make a fist. Remember that your heart is just about this
size.
Mow open and close your fist 70 times in a minute —
that's a little more than once a second.
You'll soon find out that doing this for even a minute can
be exhausting.
But the heart of most adults beats on an average 70 times a
minute. For children, the rate is higher — about 90 times a
minute.
As we go about our daily activities, our hearts are beating,
day after day, year after year. The average person's heart will
beat over 2 billion times in a lifetime.
A person's heart does not beat at the same rate all the time.
For one thing, heart rate is affected by the body's energy
needs. And these needs are constantly changing depending
on what we are doing.
15
This is Linda. Let's follow her through a typical day and
see how her heart rate varies.
As Linda wakes up, her heart rate is fairly low, perhaps 68
beats per minute.
But the rate changes as her body's cells become more active
and need more oxygen and fuel. Linda's heart rate may
increase to 75 beats per minute.
Later that morning, when Linda walks with a friend, her
heart rate probably becomes higher, perhaps 90 beats per
minute.
But when she stands still, her heart rate goes down again.
Later in the day, as she bikes, he heart rate reaches its
highest levels. With prolonged and strenuous activity, her
body needs the most oxygen and fuel.
As a result, Linda's heart rate might reach 135.
As the day ends, and activity decreases, her heart rate will
become lower again, until finally, as she drifts off to sleep, it
begins to reach its lowest levels, perhaps around 65 beats per
minute.
The heart and circulatory system are normally remarkably
efficient, but this system doesn't always work smoothly.
Things can go wrong.
Each year, millions of people suffer from heart attacks
and other disorders of the heart and blood vessels.
Heart and circulatory disorders are our nation's number
one killer, responsible for more deaths than any other disease, including cancer.
How do these problems develop? We don't know all the
answers, but we do know some things.
One thing we know is that smoking has an effect. People
who smoke heavily are more than twice as likely to suffer a
heart attack as nonsmokers.
Another thing we know is that people who have a diet high in
fat have a much greater risk. How does fat affect the heart and
blood vessels?
To answer this question, let's take another look at the inside
of an artery. If an artery is healthy, it is like a smooth and
open pipe. It allows blood to easily flow through it.
But fatty deposits can build up inside the walls of the
arteries.
As time goes on, these deposits can grow and become
16
harder, becoming what is called plaque. As a result, an artery
can become clogged.
Sometimes an artery can become blocked entirely.
If this happens to an artery that supplies blood to the
brain, brain cells will die, causing what is known as a stroke.
When this happens to an artery that supplies blood to the
heart itself, part of the muscle may die.
The result? A heart attack.
Since most victims of heart attacks and strokes are middleaged or older, people who are younger don't have to be concerned — right?
Wrong! The first indication of problems can occur in people
much younger.
Plaque that clogs arteries contains a great deal of fatty
substance called cholesterol. High levels of cholesterol have
been found in the blood of some teenagers and children.
Mot all cholesterol is bad. In fact, our bodies need a small
amount of cholesterol. But too much of the wrong type of
cholesterol can cause problems.
Unfortunately such cholesterol can be found in many of
the things we like, including hot dogs, hamburgers, cheese,
ice cream, and other fatty foods.
If foods like this can lead to problems, what kinds of food
are good?
Well, doctors recommend eating more vegetables, fruits,
peas and beans, and whole grains — like brown rice, or bread
containing whole wheat flour.
But eating too much of any kind of food can be bad for
the heart if you become overweight.
For one thing, being overweight means that the heart has
to work harder to pump blood through fatty tissue.
This brings up another point. One way to avoid becoming
overweight is to exercise.
But exercise doesn't just keep your weight down. Exercise
strengthens the heart.
The best kind of exercises for the heart are activities involving continuous motion, like cross country skiing, swimming, biking, or running. This type of exercise makes the
heart work harder and become stronger.
As the heart becomes stronger, it can pump more blood
17
with each beat and work more efficiently. Compared to an
out-of-shape heart, a strong heart can beat fewer times to
pump the same amount of blood.
In this program we've looked at many different things about
the human circulatory system and heart.
We've seen that the circulatory system consists of a vast
network of arteries, veins, and capillaries, and that these
vessels form a transport system that provides the body's cells
with food and oxygen and takes away wastes.
We've looked at blood, the fluid that flows through this
transport system, and at some of the things that make up
blood, such as red blood cells that carry oxygen, white blood
cells that help protect us against disease.
We've seen that the heart is the pump that pushes blood
through the circulatory system, and that the rate at which the
heart beats varies as a result of what we are doing. The heart
beats faster, for example, when the body's cells need more
fuel and oxygen for energy.
We've seen that while the body's circulatory system and
heart usually function smoothly, sometimes things do go
wrong. In particular, we've seen how a diet high in cholesterol
can lead to the buildup of fatty deposits in the arteries.
But we've also seen how exercise and a diet low in fat can
make the heart stronger and healthier.
And this may be the most important lesson of all — that
each of us can take responsibility for the health of our heart
and circulatory system.
THE END.
CREDITS
Author: Peter Cochran Director of
Photography: Peter Scheer Graphics and
Animation: Roger Meyer Stock Footage:
American Airlines
Encyclopedia Britannica Educational Corp.
Opening Music: Roger Meyer Narrators: Gayle Ritchie, Virgil
Roberson Consultants: Karin Rhines, Michael Worosz
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Sound: Bob Maley
Post Production Facilities: Deerfield Video Audio
Sweetening: Acme Studios Special
Appreciation to: American Airlines
Dobbs Ferry Ambulance Corps Produced for:
RAINBOW EDUCATIONAL VIDEO
by
COCHRAN COMMUNICATIONS
GLOSSARY
aorta: the main artery that leaves the heart and supplies blood
to all parts of the body except the lungs
arteries: blood vessels that carry blood away from the heart
atria: the two top chambers of the human heart; they receive
blood from veins and deliver it to the ventricles
capillaries: thin-walled blood vessels that connect arteries
and veins
cholesterol: a substance found in the fatty tissue of animals;
high levels of cholesterol in the human diet have been
associated with clogging of the arteries
circulatory system: the system in the body through which
blood circulates; consists of blood vessels and the heart
heart attack: a sudden failure of the heart
plaque: a fatty deposit that has hardened inside an artery;
plaque can block arteries, leading to a heart attack or stroke
plasma: the liquid portion of blood; consists mainly of water
and also food, chemicals, and wastes
pulse: the rhythmical stretching and relaxing of the walls of
arteries as blood flows through them
red blood cells: blood cells that deliver oxygen to cells
throughout the body
stroke: a sudden injury to the brain
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veins: blood vessels that carry blood back to the heart
white blood cells: blood cells that help defend the body
against disease
BIBLIOGRAPHY
Asimov, Isaac, How Did We Find Out About Blood?
New York: Walker, 1986.
Cole, Joanna, Cuts, Breaks, Bruises, and Burns: How Your
Body Heals. New York: Crowell, 1985.
Elgin, Kathleen, The Human Body: The Heart. New York:
Franklin Watts, 1968.
Neil, Eric, William Harvey and the Circulation of the
Blood. London: Priory Press, 1975.
LeMaster, Leslie Jean, Your Heart and Blood. Chicago:
Children's Press, 1984.
Schneider, Leo, Lifeline: The Story of the Circulatory
System. New York: Harcourt Brace, 1958.
Silverstein, Alvin and Virginia B., Circulatory Systems:
Rivers Within. Englewood Cliffs, N.J.: Prentice-Hall 1970.
Silverstein, Alvin and Virgina B., Heartbeats: Your Body,
Your Heart. New York: Lippincott, 1983.
Sterne, Emma Gelders, Blood Brothers: Four Men of
Science. New York: Knopf, 1985.
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